The present invention relates to a display device, and more particularly to a display device including a protective plate provided in the front surface of a display panel to protect the display panel.
In portable information terminals such as a mobile phone with a liquid crystal display device as a display device, the liquid crystal display device is formed by a liquid crystal display panel and a backlight device for emitting illumination light to the liquid crystal display panel. In general, the display device has a module structure in which a protective plate (front window) is fixed to the front surface (observer side surface) of the liquid crystal display device to protect the liquid crystal display panel formed of a glass substrate.
In the display device with the module structure, a frame-like light shielding film is printed on the back surface of the protective plate, namely, on the surface facing the liquid crystal display panel so as to surround the display area of the liquid crystal display panel. In particular, in order to prevent leakage of illumination light emitted from the backlight device to the outside from the periphery of the liquid crystal display module, the back surface of the protective film is recoated with the light shielding film to improve the light shielding performance.
Further, in the liquid crystal display module with this configuration, the protective plate is fixed to the liquid crystal display panel by an adhesive of thermosetting resin or photocurable resin. In this case, the adhesive is dropped on the front surface of the liquid crystal display panel, and the protective plate is placed on the top surface of the adhesive. Then, the adhesive is cured to form an adhesive layer between the liquid crystal display panel and the protective plate. In this way, the protective plate is fixed to the liquid crystal display panel.
However, the back surface of the protective plate has a difference in level due to the printing of the light shielding film. This leads to a problem that bubbles are generated in the step portion when the adhesive is applied over the back surface of the protective film, and thus the product quality is significantly reduced.
As a method for solving this problem, for example, there is a display device described in Japanese Unexamined Patent Application Publication No. 2011-7830. In the display device described in Japanese Unexamined Patent Application Publication No. 2011-7830, when the light shielding film is formed by recoating, the light shielding film is printed to form a step on the inner peripheral side of the light shielding film, to reduce the difference in level between the area where the light shielding film is not formed and the area recoated with the light shielding film, in order to prevent bubbles from forming in the step portion.